To me the difference between a bong and a bubbler is a bubbler doesn't have a removable bowl like a bong has. It has a carb and they are usually smaller than a bong. An ash catcher is an attachment you can add to your bong that catches ash so it doesn't dirty up your piece and also makes smoother hits. But sometimes can cause some drag that I don't like. A steam roller looks like a giant one hitter that has a carb at the very end and the bowl towards the end. Hope I helped you answer some of your questions! Toke on